1. Field of the Invention
The present invention relates to the field of torque measurement in general. In particular, the present invention relates specifically to a hand held torque measuring apparatus and method used primarily to measure the torque required to unscrew a closure cap from a bottle. The prior art teaches the use of fixtures with mechanical gripping surfaces and controlled environments for measuring the torque used to tighten or loosen a bottle cap. The present invention overcomes these non-real world measurements by replicating the grasping of the bottle and the turning of the cap by hand with a method for recording each test in a torque testing device.
2. Description of the Known Art
As will be appreciated by those skilled in the art, a bottle cap should be securely sealed to a bottle to prevent leaks, but should remain easily opened by the hands of a user. Twist caps have long been used to seal the contents of bottles prior to shipment and sale and provide the easy opening fixture for a user. By providing at least vestigial threads on the cap and bottle top, rotation of the cap in one direction with respect to the bottle fixedly and sealingly connects the cap to the bottle top, while rotation of the cap in the opposite direction is required to remove the cap from the bottle prior to dispensing contents of the bottle. Such a packaging system is used in a wide variety of industries for a wide variety of goods and the bottles and caps take a wide variety of forms such as soda bottles, chemical containers, medicine bottles, etc. . . . In the pharmaceutical industry, for example, the “bottle and cap” may be of various forms and materials and may be known by a variety of names. For convenience in this application, it will be understood that the terms “bottle” and “cap” are used in a broad sense and it will be understood that by a bottle with a twist cap is meant essentially in a container with a cover whose placement and removal involves a relative twisting motion.
Station based container cap torque testers are commonly used in connection with commercial container filling lines wherein plastic, glass or metal containers are filled with liquids or powders and then automatically capped by machinery which clamps the containers at a work station and rotates threaded container caps onto the containers at the work station. Variations in the torque with which the caps are tightened onto the containers occur during the capping process for a number of reasons, including changes in manufacturing tolerances for the threaded container caps and containers, variations in pneumatic line pressures and electrical voltages employed in the machinery used in the container capping operation, wear on the container clamping and/or cap grasping members employed therein, and changes in ambient temperature and humidity during the container capping operation.
The variations in the torque with which the caps are tightened onto the containers results in the another arising of potentially significant problems in connection with the handling and/or usage of the capped containers. For example, containers having insufficiently torqued container caps are subject to leakage during packing and shipping, and containers having caps which are excessively torqued present problems for the ultimate consumer when he or she attempts to remove the container cap to use the product therein.
Torque testers have been employed to check the torque level at which container caps have been applied to containers. Previously utilized torque testers have been used to clamp a bottle using either the lifter ring or the petaloid shape to hold the bottle in position. By using the lifter ring, an accurate reading of the head to cap measurement is obtained, but the measurement fails to measure the real world torque due to the deflection caused by the thin walled plastic of the bottle such as that found in soda bottles. The petaloid bottom clamping systems may prove to be inaccurate due to the full deflection of the bottle across the entire vertical span of the bottle. With the advent of highly efficient bottle designs which are continuously reducing the amount of plastic or material in the bottle, it is becoming extremely desirable to obtain quick accurate measurements of the real world bottle opening torque.
Strain gauges based on piezo-resistance effect, are well known. Metal and alloy wires were used as an early form of strain gauge and more recently, thin sheets of metal or foil bonded to the surface of an object in which the strain is to be measured, or thin films evaporated onto the surface of such an object, or thin pieces of semiconductor material bonded onto such a surface have all been used. All of these devices are capable of providing accurate and repeatable indications of the magnitude of both tensile and compressive strain on the surface of an underlying supporting member. Such devices are widely used in the field of precision engineering for strain measurement or stress analysis or in the manufacture of high quality transducers such as load cells or force or pressure transducers for the measurement of force, pressure or weight. Sophisticated industrial weighing systems and weighing platforms and expensive weighing machines or scales used in trade or commerce are provided for by these known devices which can frequently measure to an accuracy of 0.1% or better under all required operating conditions.
Also of note in the prior art is the description of the circuit board and microprocessor based engine used in the present invention. The MC2000-077 is designed for general use applications of moderate size, especially those that require powerful communication functions and low power usage, on a physically tiny device. The MC2000-077 features five 10 bit A/D signals, up to 21 DIO signals, 2 serial connectors on the Dev-07X board (COM & DEV), with the option of adding two more using the V2Serial peripheral. Low-power modes can be controlled with Vesta Basic. The MC2000-077 provides users with a feature-packed programming environment. The device features 32-KB application space, 10-bit ADCs, powerful communications capabilities, and background monitoring of 12 digital bits. The MC2000-077 provides 100 bytes of variable RAM space and sports an enhanced version of Vesta Basic, supporting four buffered serial ports, (three with 8-byte buffers and one with a 72-byte buffer), and enhanced communications functions. And, it comes in a tiny (0.962×0.962) package. The MC2000-077 provides signal support for five 10-bit ADCs, 21 DIO, two serial ports, an LCD, a keypad, and a Vesta Addressable Synchronous Transfer (VAST) bus. The new Dev-07X prototyping board provides connectors for development purposes. Two additional serial ports are available using the VAST V2SERIAL board. The VAST bus provides signal access to a range of Vesta peripherals including various relays, opto-isolated inputs, 8-, 10-, 12-, and 24-bit ADCs, multiple ADC and DIO combinations, and various LED options. RS-232 signals on the Dev-07X board can be easily converted to RS-485 with a RS-485 adapter.
Numerous torque and related testing devices are illustrated in the patent database including: United States Statutory Invention Registration Number H1777 published Feb. 2, 1999 for Colby; U.S. Pat. No. 164,100 issued to Plymale on Jun. 8, 1875; U.S. Pat. No. 2,365,419 issued to Lockheed on Dec. 19, 1944; U.S. Pat. No. 2,791,904 issued to Campbell on May 14, 1957; U.S. Pat. No. 3,866,463 issued to Smith on Feb. 18, 1975; U.S. Pat. No. 4,506,250 issued to Kirby on Mar. 19, 1985; U.S. Pat. No. 4,315,427 issued to Leiter on Feb. 16, 1982; U.S. Pat. No. 4,539,852 issued to Feld on Sep. 10, 1985; U.S. Pat. No. 4,494,358 issued to Zalkin on Jan. 22, 1985; U.S. Pat. No. 4,674,340 issued to Burt on Jun. 23, 1987; U.S. Pat. No. 4,716,772 issued to Bubeck on Jan. 5, 1988; U.S. Pat. No. 4,794,801 issued to Andrews on Jan. 3, 1989; U.S. Pat. No. 4,808,976 issued to Kiefer on Feb. 28, 1989; U.S. Pat. No. 4,811,850 issued to Bankuty on Mar. 14, 1989; U.S. Pat. No. 4,976,159 issued to Snyder on Dec. 11, 1990; U.S. Pat. No. 5,107,727 issued to Kiefbeck on Apr. 28, 1992; U.S. Pat. No. 5,501,107 issued to Snyder on Mar. 26, 1996; U.S. Pat. No. 5,319,984 issued to Humphries on Jun. 14, 1994; and U.S. Pat. No. 5,415,050 issued to Trendel on May 16, 1995. Each of these patents are hereby incorporated by reference in their entirety.
U.S. Pat. No. 4,506,250 discloses a strain gauge or transducer is provided incorporating a supported film electrical resistance element whose electrical resistance varies as a function of applied mechanical strain and is provided with electrically conductive terminals. The resistance element comprises a dispersion of electrically conductive or resistive particles in an organic polymer together with an optional electrically insulating filler material. In a particular embodiment, the resistance element is supported on a member of anodized aluminum.
U.S. Statutory Invention Registration No. H1777 issued to Colby on Feb. 2, 1999 describes a torque wrench for manually applying a screw cap on a threaded opening of a container. The torque wrench includes a handle portion which engages a dome that releasably receives a neck ring insert. The insert engages the cap and applies a consistent amount of torque thereto by the use of a draft angle or curved portion on an inner surface which tightly engages the curved top edge of the cap. The insert may be sized to accommodate different sized caps.
U.S. Pat. No. 2,791,904 issued to Campbell on May 31, 1955 describes an improved tool for testing and adjusting the torque of a screw or the like on a small assembly which can be held in the hand of the operator.
U.S. Pat. No. 4,539,852 issued to Feld on Sep. 10, 1985 describes a vial cap torque tester which is capable of measuring the torque required to turn a cap, typically made of aluminum, on a rubber stoppered vial. The torque tester of the invention is comprised of a base which holds a torque gauge. The torque gauge has a gripper adapted to hold the bottom of a vial thereon. The device is further comprised of an apparatus for attaching to and turning the cap of the vial. That device is comprised of a spring having an inner diameter which is somewhat less than the outer diameter of the aluminum cap which compresses the rubber stopper on the vial. The spring is attached to a cylindrical handle at one end and to a concentric cylindrical housing at the other end. A torque arm is connected to the cylindrical housing such that by turning the torque arm relative to the cylindrical handle in a direction which opens the coils of the spring, the spring can be placed over the cap. Another release of the handle relative to the torque arm causes the spring to close down upon the cap. If a turning force is applied to the torque arm in the direction which closes the coils of the spring, the cap will be held tightly while the vial turns the torque tester to achieve a maximum torque prior to slippage of the cap on the vial. At the point of slippage of the cap on the neck of the vial, the maximum torque registered by the torque gauge indicates the actual amount of torque required to cause slippage of the cap.
Such devices do not, however, provide a solution to the need for low cost simple forms of force measuring transducers or hand-held recordable torque measuring devices such as bottle capping, or for simple industrial control purposes.
It is therefore an object of the invention to provide a torque measurement device that is ergonomically held in ones hand.
It is another object of the invention to provide a torque measurement device that does not require an external work holder.
It is another object of the invention to provide a torque measurement device that can be held in many different positions as to mimic the natural movement of a human hand.
It is another object of the invention to provide an easy to read display with memory to record the data.
It is another object of the invention to provide a device with simple push button controls.
Thus, it may be seen that these prior art patents are very limited in their teaching and utilization, and an improved torque measuring device is needed to overcome these limitations.